Hello Marc,
I think you are being wise in questioning this issue, since the consequence of actual low oil pressure can be serious. Perhaps it would be useful to have some basic information, and as simple as it may sound, confirmation that the oil is up to the required level. Yes, a bit basic, but you cannot ignore the fact that not enough oil was put in, or indeed there isn't an oil leak at the filter, drain plug or somewhere else.
You will also need to know what grade if oil has been used and to let us know what mileage this engine has done. All things being equal, it could - just could - be as simple as a suspect oil pressure switch, but your really do need to get the actual oil pressure measured with a gauge to know exactly where you are with this.
Assuming correct oil level and grade, no leaks, then I think there is some urgency in getting the actual pressure checked.
Hope some of this helps and you are able to let us know.
Good luck with it.
Kind regards, Gareth.